"Retardant" cloth, as mentioned above, from a UK supplier:
http://www.fabricuk.com/fabrics.php?...e=278#dataform

These are probably overkill, but a supplier of cloth for serious applications (welding cloth, etc.) I'd suggest looking into Nomex.
http://www.thermostatic.com/cloth.shtml

Good luck, and I hope you'll link a picture of the design / final product! I just completed a few items myself, hopefully I'll have pics up in a bit.

Edit: On the second site, anything with an "MSDS" (material safety data sheet) should be avoided.